This invention relates to the construction of buildings and, more particularly, to the reinforcement of cementitious building walls to resist damage produced by seismically induced forces.
There are thousands of buildings located in the earthquake-prone regions of the world whose cementitious walls are susceptible to seismically induced damage. (As used herein unless otherwise indicated, "cementitious" walls include cement or concrete walls made of either masonry or poured construction, which do of do not contain internal steel reinforcing structure.) During an earthquake, the ground upon which the building rests moves laterally and/or vertically. These ground motions are transmitted through the building foundation and thence into the building walls as force responses. The walls may be cracked as a result of the ground motions or, if the motions are sufficiently severe, the walls may fail completely and collapse.
The ground motions produce force response components in the building wall that lie in the plane of the building wall or out of the plane of the building wall. The nature of the ground motions and force responses at any particular location that might result from an earthquake cannot be predicted with complete certainty. However, in many cases the predominant mode of ground motion and the resulting forces on the walls can be estimated. That is, an engineer who analyzes a building and the geological fault structure in its vicinity can often predict that a wall would likely be subject to particular force components that are out-of-plane, vertical in-plane, and horizontal in-plane, where the "plane" refers to the plane of the wall. The present invention is directed toward reinforcement of cementitious building walls to resist damage induced by such in-plane forces and out-of-plane forces, also termed "flexural" response.
It has been known to externally reinforce building walls to resist damage induced by seismic movements. Studies by the inventors have determined that different modes of seismic forces require different types of external reinforcement for optimal damage resistance, and have further shown that some of the most common modes of external reinforcement may have little beneficial effect in resisting cracking and/or failing of the building walls in many cases. There is, therefore, a need for improved approaches to external reinforcement of cementitious building walls to resist damage caused by various types of force and motion components, which are optimized for particular force responses in the building walls. The present invention fulfills this need, and further provides related advantages.